From b6e51316daede0633e9274e1e30391cfa4747877 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Wed, 16 Sep 2009 15:13:54 +0200 Subject: [PATCH] writeback: separate starting of sync vs opportunistic writeback bdi_start_writeback() is currently split into two paths, one for WB_SYNC_NONE and one for WB_SYNC_ALL. Add bdi_sync_writeback() for WB_SYNC_ALL writeback and let bdi_start_writeback() handle only WB_SYNC_NONE. Push down the writeback_control allocation and only accept the parameters that make sense for each function. This cleans up the API considerably. Signed-off-by: Jens Axboe --- fs/fs-writeback.c | 132 ++++++++++++++++++++++---------------------- fs/ubifs/budget.c | 20 +------ include/linux/backing-dev.h | 2 +- include/linux/writeback.h | 4 +- mm/page-writeback.c | 12 +--- 5 files changed, 75 insertions(+), 95 deletions(-) diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 59b3ee6..5887328 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -74,14 +74,10 @@ static inline bool bdi_work_on_stack(struct bdi_work *work) } static inline void bdi_work_init(struct bdi_work *work, - struct writeback_control *wbc) + struct wb_writeback_args *args) { INIT_RCU_HEAD(&work->rcu_head); - work->args.sb = wbc->sb; - work->args.nr_pages = wbc->nr_to_write; - work->args.sync_mode = wbc->sync_mode; - work->args.range_cyclic = wbc->range_cyclic; - work->args.for_kupdate = 0; + work->args = *args; work->state = WS_USED; } @@ -194,7 +190,7 @@ static void bdi_wait_on_work_clear(struct bdi_work *work) } static void bdi_alloc_queue_work(struct backing_dev_info *bdi, - struct writeback_control *wbc) + struct wb_writeback_args *args) { struct bdi_work *work; @@ -204,7 +200,7 @@ static void bdi_alloc_queue_work(struct backing_dev_info *bdi, */ work = kmalloc(sizeof(*work), GFP_ATOMIC); if (work) { - bdi_work_init(work, wbc); + bdi_work_init(work, args); bdi_queue_work(bdi, work); } else { struct bdi_writeback *wb = &bdi->wb; @@ -214,24 +210,54 @@ static void bdi_alloc_queue_work(struct backing_dev_info *bdi, } } -void bdi_start_writeback(struct writeback_control *wbc) +/** + * bdi_sync_writeback - start and wait for writeback + * @bdi: the backing device to write from + * @sb: write inodes from this super_block + * + * Description: + * This does WB_SYNC_ALL data integrity writeback and waits for the + * IO to complete. Callers must hold the sb s_umount semaphore for + * reading, to avoid having the super disappear before we are done. + */ +static void bdi_sync_writeback(struct backing_dev_info *bdi, + struct super_block *sb) { - /* - * WB_SYNC_NONE is opportunistic writeback. If this allocation fails, - * bdi_queue_work() will wake up the thread and flush old data. This - * should ensure some amount of progress in freeing memory. - */ - if (wbc->sync_mode != WB_SYNC_ALL) - bdi_alloc_queue_work(wbc->bdi, wbc); - else { - struct bdi_work work; + struct wb_writeback_args args = { + .sb = sb, + .sync_mode = WB_SYNC_ALL, + .nr_pages = LONG_MAX, + .range_cyclic = 0, + }; + struct bdi_work work; - bdi_work_init(&work, wbc); - work.state |= WS_ONSTACK; + bdi_work_init(&work, &args); + work.state |= WS_ONSTACK; - bdi_queue_work(wbc->bdi, &work); - bdi_wait_on_work_clear(&work); - } + bdi_queue_work(bdi, &work); + bdi_wait_on_work_clear(&work); +} + +/** + * bdi_start_writeback - start writeback + * @bdi: the backing device to write from + * @nr_pages: the number of pages to write + * + * Description: + * This does WB_SYNC_NONE opportunistic writeback. The IO is only + * started when this function returns, we make no guarentees on + * completion. Caller need not hold sb s_umount semaphore. + * + */ +void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages) +{ + struct wb_writeback_args args = { + .sync_mode = WB_SYNC_NONE, + .nr_pages = nr_pages, + .range_cyclic = 1, + }; + + bdi_alloc_queue_work(bdi, &args); } /* @@ -863,23 +889,25 @@ int bdi_writeback_task(struct bdi_writeback *wb) } /* - * Schedule writeback for all backing devices. Can only be used for - * WB_SYNC_NONE writeback, WB_SYNC_ALL should use bdi_start_writeback() - * and pass in the superblock. + * Schedule writeback for all backing devices. This does WB_SYNC_NONE + * writeback, for integrity writeback see bdi_sync_writeback(). */ -static void bdi_writeback_all(struct writeback_control *wbc) +static void bdi_writeback_all(struct super_block *sb, long nr_pages) { + struct wb_writeback_args args = { + .sb = sb, + .nr_pages = nr_pages, + .sync_mode = WB_SYNC_NONE, + }; struct backing_dev_info *bdi; - WARN_ON(wbc->sync_mode == WB_SYNC_ALL); - rcu_read_lock(); list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) { if (!bdi_has_dirty_io(bdi)) continue; - bdi_alloc_queue_work(bdi, wbc); + bdi_alloc_queue_work(bdi, &args); } rcu_read_unlock(); @@ -891,17 +919,10 @@ static void bdi_writeback_all(struct writeback_control *wbc) */ void wakeup_flusher_threads(long nr_pages) { - struct writeback_control wbc = { - .sync_mode = WB_SYNC_NONE, - .older_than_this = NULL, - .range_cyclic = 1, - }; - if (nr_pages == 0) nr_pages = global_page_state(NR_FILE_DIRTY) + global_page_state(NR_UNSTABLE_NFS); - wbc.nr_to_write = nr_pages; - bdi_writeback_all(&wbc); + bdi_writeback_all(NULL, nr_pages); } static noinline void block_dump___mark_inode_dirty(struct inode *inode) @@ -1048,7 +1069,7 @@ EXPORT_SYMBOL(__mark_inode_dirty); * on the writer throttling path, and we get decent balancing between many * throttled threads: we don't want them all piling up on inode_sync_wait. */ -static void wait_sb_inodes(struct writeback_control *wbc) +static void wait_sb_inodes(struct super_block *sb) { struct inode *inode, *old_inode = NULL; @@ -1056,7 +1077,7 @@ static void wait_sb_inodes(struct writeback_control *wbc) * We need to be protected against the filesystem going from * r/o to r/w or vice versa. */ - WARN_ON(!rwsem_is_locked(&wbc->sb->s_umount)); + WARN_ON(!rwsem_is_locked(&sb->s_umount)); spin_lock(&inode_lock); @@ -1067,7 +1088,7 @@ static void wait_sb_inodes(struct writeback_control *wbc) * In which case, the inode may not be on the dirty list, but * we still have to wait for that writeout. */ - list_for_each_entry(inode, &wbc->sb->s_inodes, i_sb_list) { + list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { struct address_space *mapping; if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE|I_NEW)) @@ -1107,14 +1128,8 @@ static void wait_sb_inodes(struct writeback_control *wbc) * for IO completion of submitted IO. The number of pages submitted is * returned. */ -long writeback_inodes_sb(struct super_block *sb) +void writeback_inodes_sb(struct super_block *sb) { - struct writeback_control wbc = { - .sb = sb, - .sync_mode = WB_SYNC_NONE, - .range_start = 0, - .range_end = LLONG_MAX, - }; unsigned long nr_dirty = global_page_state(NR_FILE_DIRTY); unsigned long nr_unstable = global_page_state(NR_UNSTABLE_NFS); long nr_to_write; @@ -1122,9 +1137,7 @@ long writeback_inodes_sb(struct super_block *sb) nr_to_write = nr_dirty + nr_unstable + (inodes_stat.nr_inodes - inodes_stat.nr_unused); - wbc.nr_to_write = nr_to_write; - bdi_writeback_all(&wbc); - return nr_to_write - wbc.nr_to_write; + bdi_writeback_all(sb, nr_to_write); } EXPORT_SYMBOL(writeback_inodes_sb); @@ -1135,21 +1148,10 @@ EXPORT_SYMBOL(writeback_inodes_sb); * This function writes and waits on any dirty inode belonging to this * super_block. The number of pages synced is returned. */ -long sync_inodes_sb(struct super_block *sb) +void sync_inodes_sb(struct super_block *sb) { - struct writeback_control wbc = { - .sb = sb, - .bdi = sb->s_bdi, - .sync_mode = WB_SYNC_ALL, - .range_start = 0, - .range_end = LLONG_MAX, - }; - long nr_to_write = LONG_MAX; /* doesn't actually matter */ - - wbc.nr_to_write = nr_to_write; - bdi_start_writeback(&wbc); - wait_sb_inodes(&wbc); - return nr_to_write - wbc.nr_to_write; + bdi_sync_writeback(sb->s_bdi, sb); + wait_sb_inodes(sb); } EXPORT_SYMBOL(sync_inodes_sb); diff --git a/fs/ubifs/budget.c b/fs/ubifs/budget.c index 1c8991b..ee1ce68 100644 --- a/fs/ubifs/budget.c +++ b/fs/ubifs/budget.c @@ -54,29 +54,15 @@ * @nr_to_write: how many dirty pages to write-back * * This function shrinks UBIFS liability by means of writing back some amount - * of dirty inodes and their pages. Returns the amount of pages which were - * written back. The returned value does not include dirty inodes which were - * synchronized. + * of dirty inodes and their pages. * * Note, this function synchronizes even VFS inodes which are locked * (@i_mutex) by the caller of the budgeting function, because write-back does * not touch @i_mutex. */ -static int shrink_liability(struct ubifs_info *c, int nr_to_write) +static void shrink_liability(struct ubifs_info *c, int nr_to_write) { - int nr_written; - - nr_written = writeback_inodes_sb(c->vfs_sb); - if (!nr_written) { - /* - * Re-try again but wait on pages/inodes which are being - * written-back concurrently (e.g., by pdflush). - */ - nr_written = sync_inodes_sb(c->vfs_sb); - } - - dbg_budg("%d pages were written back", nr_written); - return nr_written; + writeback_inodes_sb(c->vfs_sb); } /** diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h index 859e797..0ee33c2 100644 --- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -101,7 +101,7 @@ int bdi_register(struct backing_dev_info *bdi, struct device *parent, const char *fmt, ...); int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev); void bdi_unregister(struct backing_dev_info *bdi); -void bdi_start_writeback(struct writeback_control *wbc); +void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages); int bdi_writeback_task(struct bdi_writeback *wb); int bdi_has_dirty_io(struct backing_dev_info *bdi); diff --git a/include/linux/writeback.h b/include/linux/writeback.h index 48a054e..75cf586 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -68,8 +68,8 @@ struct writeback_control { */ struct bdi_writeback; int inode_wait(void *); -long writeback_inodes_sb(struct super_block *); -long sync_inodes_sb(struct super_block *); +void writeback_inodes_sb(struct super_block *); +void sync_inodes_sb(struct super_block *); void writeback_inodes_wbc(struct writeback_control *wbc); long wb_do_writeback(struct bdi_writeback *wb, int force_wait); void wakeup_flusher_threads(long nr_pages); diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 12c3d843..1eea4fa 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -582,16 +582,8 @@ static void balance_dirty_pages(struct address_space *mapping) if ((laptop_mode && pages_written) || (!laptop_mode && ((nr_writeback = global_page_state(NR_FILE_DIRTY) + global_page_state(NR_UNSTABLE_NFS)) - > background_thresh))) { - struct writeback_control wbc = { - .bdi = bdi, - .sync_mode = WB_SYNC_NONE, - .nr_to_write = nr_writeback, - }; - - - bdi_start_writeback(&wbc); - } + > background_thresh))) + bdi_start_writeback(bdi, nr_writeback); } void set_page_dirty_balance(struct page *page, int page_mkwrite) -- 2.7.4